Showing papers in "Soil Science Society of America Journal in 2014"
TL;DR: In this paper, a review of P NMR studies of soil has been presented, including pre-and post-extraction treatments, the physical state of the soil sample at the time of extraction, extraction length, extraction ratio, soil/extractant ratio, P recovery, P in residues, methods to concentrate extracts, redissolving samples for ³¹P NMR experiments, and the use of the internal standard methylene diphosphonic acid.
Abstract: Phosphorus nuclear magnetic resonance (³¹P NMR) spectroscopy is an important tool for the study of soil P and has significantly advanced our knowledge of soil P forms, particularly organic P; however, it must be used correctly to provide meaningful results. This review covers the ³¹P NMR studies of soil published from 2005 to 2013. The first part discusses preparing samples for ³¹P NMR, including extractants, pre- and post-extraction treatments, the physical state of the soil sample at the time of extraction, extraction length, the soil/extractant ratio, P recovery, P in residues, methods to concentrate extracts, redissolving samples for ³¹P NMR experiments, the use of the internal standard methylene diphosphonic acid, and the potential for degradation with any of these steps. The second part of this review focuses on NMR experiment parameters, including delay times, proton decoupling, and experiment length. Potential concerns in these areas are noted, and suggestions are given for procedures to optimize the information obtained from a ³¹P NMR experiment.
194 citations
TL;DR: Krolson et al. as mentioned in this paper proposed a method for determining organic carbon sequestration rates in soil and water management and conservation based on the Soil Science Society of America (SSSaj).
Abstract: Soil Sci. Soc. Am. J. 78:348–360 doi:10.2136/sssaj2013.09.0412 Open Access Received 24 Sept. 2013. *Corresponding author (krolson@illinois.edu). © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Experimental Consideration, Treatments, and Methods in Determining Soil Organic Carbon Sequestration Rates Review & Analysis–Soil & Water Management & Conservation
124 citations
120 citations
TL;DR: Lotfollah et al. as mentioned in this paper investigated the effect of cover crop effects on soil quality and the Tillage System and Cover Crop Effects on Soil Quality in the field of Soil Science.
Abstract: Soil Sci. Soc. Am. J. doi:10.2136/sssaj 2013.07.0301 Received 26 July 2013 *Corresponding author (lotfollah.abdollahi@agrsci.dk; Lotfollah.abdollahi@yahoo.com) © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Tillage System and Cover Crop Effects on Soil Quality: I. Chemical, Mechanical, and Biological Properties Soil & Water Management & Conservation
118 citations
TL;DR: Baldrian et al. as discussed by the authors described the distribution of Extracellular Enzymes in Soils: Spatial Heterogeneity and Determining Factors at Various Scales.
Abstract: Soil Sci. Soc. Am. J. 78:11–18 doi:10.2136/sssaj2013.04.0155dgs Received 28 Apr. 2013 *Corresponding author (baldrian@biomed.cas.cz). © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Distribution of Extracellular Enzymes in Soils: Spatial Heterogeneity and Determining Factors at Various Scales
116 citations
112 citations
TL;DR: Soil organic matter, particulate organ- ic matter, and potentially mineralizable N (PMN) were measured for two depth layers in both the corn silage and soybean phases of the rotation and apparently, a rye cover crop grown only after soybean did not add enough residues to the soil to cause measureable changes in SOM, POM, or PMN.
Abstract: Corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] farmers in the upper Midwest are showing increasing interest in winter cover crops. The effects of winter cover crops on soil quality in this region, however, have not been investigated extensively. The objective of this experiment was to determine the effects of a cereal rye (Secale cereale L.) winter cover crop after more than 9 yr in a corn silage–soybean rotation. Four cereal rye winter cover crop treatments were established in 2001: no cover crop, rye after soybean, rye after silage, and rye after both. Soil organic matter (SOM), particulate organ- ic matter (POM), and potentially mineralizable N (PMN) were measured in 2010 and 2011 for two depth layers (0–5 and 5–10 cm) in both the corn silage and soybean phases of the rotation. In the 0- to 5-cm depth layer, a rye cover crop grown after both main crops had 15% greater SOM, 44% greater POM, and 38% greater PMN than the treatment with no cover crops. In gen- eral, the treatments that had a rye cover crop after both crops or after corn silage had a positive effect on the soil quality indicators relative to treatments without a cover crop or a cover crop only after soybean. Apparently, a rye cover crop grown only after soybean did not add enough residues to the soil to cause measureable changes in SOM, POM, or PMN. In general, rye cover crop effects were most pronounced in the top 5 cm of soil.
109 citations
TL;DR: The Detritus Input and Removal Treatments (DIRT) experiment at Harvard Forest was designed to assess how rates and sources of plant litter inputs control the accumulation and dynamics of organic matter in soils across decadal time scales as discussed by the authors.
Abstract: Understanding controls on C stored in soil organic matter (SOM) is of critical importance to models of biospheric C sequestration. Although ecosystem C models assume a strong relationship between plant litter inputs and soil C accumulation, there is little experimental evidence to support this assumption. The Detritus Input and Removal Treatments (DIRT) experiment at Harvard Forest was designed to assess how rates and sources of plant litter inputs control the accumulation and dynamics of organic matter in soils across decadal time scales. Carbon and SOM quantity and quality were measured in O horizon and mineral soil in five treatments: control, double litter, no litter, no roots, and no inputs. After 20 yr of manipulation, doubling litter inputs did not increase bulk soil C or N content, light or heavy fraction pools of C, or measures of labile C. However, the activities of two key enzymes (b-glucosidase and phosphomonoesterase) increased 30% with litter additions. Exclusion of either aboveground litter or root inputs resulted in sharp declines in O-horizon C and N but smaller decreases in total mineral soil C and N. However, decreases in light fraction C and soil respiration were significant in removal treatments. Litter exclusion resulted in an 18% decline in total profile mineral soil C, whereas root exclusion resulted in a 9% decline, indicating the importance of aboveground inputs to long-term C pools. Soil C pools in this forest do not respond linearly or immediately to aboveground or belowground litter inputs, and thus efforts to sequester C by managing productivity and associated litter inputs will probably not result in increased C storage in short time frames. Abbreviations: DL, double litter; NI, no inputs; NL, no litter; NR, no roots; OA-less; plots with the O and A horizons removed and replaced with mineral soil; SOM, soil organic matter.
103 citations
TL;DR: In this paper, the effects of heavy and storm rainfall intensity and steep slope gradients on the infiltration, runoff, and soil loss of colluvial soil were investigated, and single and multiple-peak models illustrated the two types of changes for the sediment yield process.
Abstract: Rainfall intensity and slope gradient are important factors that affect soil erosion; however, contradictory observations have been made due to different experimental conditions and materials. Colluvial deposits with loose, coarse material and steep slopes are easily erodible, but the erosion mechanism of colluvial deposition remains obscure. This work investigated the effects of heavy and storm rainfall intensity and steep slope gradients on the infiltration, runoff, and soil loss of colluvial soil. The rainfall intensity ranged from 1.00 to 2.33 mm min⁻¹, and the slope gradient ranged from 36 to 84%. The infiltration rates declined sharply in the initial stage, whereas an opposite trend was observed for runoff rates until a steady state was reached after 5 min. Single- and multiple-peak models illustrated the two types of changes for the sediment yield process. The infiltration volume and the coefficient increased with increasing rainfall intensity and decreased with increasing slope, whereas the runoff coefficient decreased with increasing rainfall intensity and increased with increasing slope. Runoff volume and sediment yield increased with increasing rainfall intensity but had a critical slope gradient of 58% and >47%. The sediment concentration increased with increasing rainfall intensity, and first increased and then decreased with increasing slope gradients at rainfall intensities of 1.00 and 1.33 mm min⁻¹ but increased at rainfall intensities of 1.67, 2.00, and 2.33 mm min⁻¹. The findings of this study can be used to clarify the erosion mechanisms in disturbed soils with high coarse particle content.
102 citations
TL;DR: In this article, the authors used depth as a predictor variable to improve the prediction accuracy of RFM especially at lower depth intervals, and used these results for producing soil function maps for national agricultural planning and in assessments of environmental sustainability.
Abstract: All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. upper part of Maiduguri and Sokoto), to finer texture (loam to clay loam) toward the western part of the Niger Delta region in the south. The inclusion of depth as a predictor variable significantly improved the prediction accuracy of RFM especially at lower depth intervals. These results could be used for producing soil function maps for national agricultural planning and in assessments of environmental sustainability. T here is a growing need for spatially continuous and quantitative soil information for environmental modeling and management (Minasny et al., 2008), especially at the national and supranational scale. Soil information is essential for global environmental challenges including climate change, food and water shortage, land degradation, and loss of biodiversity (Hartemink and McBratney, 2008). Such information is not always available at the required scale and coverage and in the right format (McBratney et al., 2003; Greve et al., 2012a). This is of concern in data-scarce countries where efforts for adequate soil data collection are often hampered by economic and logistic constraints. The texture of the soil is one of its most important characteristics. It strongly affects water and nutrient retention, infiltration, drainage, aeration, SOC content, pH buffering, and porosity and that affects many soil functions and mechanical properties. Soil texture is used at all levels in classification systems, and in soil tax
101 citations
TL;DR: The purpose of this review is to describe the steps involved in producing a soil metagenome, including some of the potential pitfalls associated with its production and annotation, and possible solutions to some of these challenges.
Abstract: Technological advances in sequencing technologies and bioinformatics analysis tools now enable the generation of a metagenome from soil, although the ultimate goal of obtaining the entire complement of all genes of all organisms in a given sample of soil still lies in the future. The rich information obtained from a soil metagenome will undoubtedly provide new insights into the taxonomic and functional diversity of soil microorganisms; the question is whether it will also yield greater understanding of how C, N, and other nutrients cycle in soil. The purpose of this review is to describe the steps involved in producing a soil metagenome, including some of the potential pitfalls associated with its production and annotation. Possible solutions to some of these challenges are presented. Selected examples from published soil metagenomic studies are discussed, with an emphasis on clues that they have provided about biogeochemical cycling.
TL;DR: In this article, the authors examine valuation concepts, and ask why we might attempt to economically value the contribution of soils to the provision of ecosystem services, and examine economic valuation methods and review economic valuation of soils by surveying prices of soils on the web.
Abstract: The ecosystem services approach endeavors to incorporate the economic value of ecosystems into decision making This is because many natural resources are subject to market failure As a result, many economic decisions omit the impact that natural resource use has on the earth’s resources and the life support system it provides Hence, one of the objectives of the ecosystem services approach is to employ economic valuation of natural resources in micro- and macroeconomic policy design, implementation, and evaluation In this article we examine valuation concepts, and ask why we might attempt to economically value the contribution of soils to the provision of ecosystem services We go on to examine economic valuation methods and review economic valuation of soils By surveying prices of soils on the web we are able to make a first, limited global assessment of direct market value of topsoil prices We then consider other research efforts to value soil Finally, we consider how the valuation of soil can meaningfully be used in the introduction of improved resource management mechanisms such as decision support tools on which valuation can be based, within the UN’s System of Environmental and Economic Accounts (SEEA) and policy mechanisms like Payments for Ecosystem Services (PES)
TL;DR: In this paper, the effects of maize production with FMRF and its effect on soil organic C (SOC) concentration were investigated for five consecutive years from 2008 to 2012 on the Loess Plateau of China.
Abstract: Alleviating the hydrothermal limitations to growth, clear film fully mulched ridge-furrow (FMRF) cropping significantly improves maize (Zea mays L.) grain yield on the Loess Plateau of China. Major concerns for FMRF cropping are the stability of maize productivity and whether the system is detrimental to the soil organic C (SOC) balance under changed hydrothermal conditions. We investigated the effects of maize production with FMRF and its effect on SOC concentration for five consecutive years from 2008 to 2012. Three treatments were imposed: no mulch (narrow ridges with the crop sown beside the ridges), half mulch (the same as no mulch, except the narrow ridges were mulched), and full mulch (i.e., FMRF; alternate narrow and wide ridges, all mulched, with maize in furrows). The 5-yr average of the grain yield was 3.8 Mg ha(-1) under no mulch. Half and full mulch increased the grain yield by 68 and 102%, respectively, relative to no mulch. Root biomass was 69 and 104% greater under half and full mulch, respectively, than no mulch. The maize yield and biomass differed among years depending on the growing-season precipitation and its distribution, but the increased yield and biomass from mulching was consistent in all years. The mulch stimulated SOC mineralization and enzymatic activity but had no effect on light (density <1.8 g cm(-3)) and total SOC concentrations compared with no mulch. We conclude that increased SOC mineralization under FMRF was offset by increased SOC addition; FMRF cropping increased maize productivity without detriment to the SOC balance.
TL;DR: Tamburini et al. as mentioned in this paper investigated the role of oxygen isotopes in unraveling phosphorus transformations in the Soil-Plant System and found that oxygen isotope is essential for plant growth.
Abstract: Soil Sci. Soc. Am. J. 78:38–46 doi:10.2136/sssaj2013.05.0186dgs Received 20 May 2013. *Corresponding author (federica.tamburini@usys.ethz.ch). © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Oxygen Isotopes for Unraveling Phosphorus Transformations in the Soil–Plant System: A Review
TL;DR: In this paper, the authors examined the impacts of a one-time biochar application on net N mineralization and greenhouse gas emissions in an irrigated, calcareous soil; yet such applications are hypothesized as a means of sequestering atmospheric CO2 and improving soil quality.
Abstract: Few multiyear field studies have examined the impacts of a one-time biochar application on net N mineralization and greenhouse gas emissions in an irrigated, calcareous soil; yet such applications are hypothesized as a means of sequestering atmospheric CO2 and improving soil quality. We fall-applied four treatments, stockpiled dairy manure (42 Mg/ha dry wt.); hardwood-derived biochar (22.4 Mg/ha); combined biochar and manure; and no amendments (control). Nitrogen fertilizer was applied in all plots and years based on treatment’s pre-season soil test N and crop requirements, and accounting for estimated N mineralized from added manure. From 2009 to 2011 we measured greenhouse gas fluxes using vented chambers, net N mineralization (NNM) using buried bags, corn yield, and N uptake, and in a succeeding year, root and shoot biomass and biomass C and N concentrations. Both amendments produced soil produced persistent soil effects. Manure increased seasonal and three year cumulative NNM, root biomass, and root:shoot ratio 1.6-fold, CO2-C gas flux 1.2-fold, and reduced soil NH4:NO3 ratio 58% relative to no-manure treatments. Relative to all other treatments on average, biochar-only produced 33% less cumulative NNM, 20% less CO2-C and 50% less N2O-N gas emissions, 35% less root biomass, and increased soil NH4:NO3 ratio 1.8-fold. These long-term effects suggest that biochar slightly impaired nitrification and N immobilization processes, and are likely caused by enduring biochar porosity and surface chemistry characteristics that influence N-transform-ation processes, alter microbial populations, and sequester soil ammonium. While the biochar-only treatment demonstrated a potential to increase corn yields and minimize CO2-C and N2O-N gas emissions in these calcareous soils; biochar also caused decreased corn yields under certain soil nutrient conditions. Combining biochar with manure effectively utilizes these soil amendments as it eliminated potential yield reductions and maximized manure net N mineralization potential.
TL;DR: Lotfollah et al. as discussed by the authors investigated the effect of cover crop effects on soil quality and showed that cover crop affects soil quality significantly more than the traditional cover crop effect on soil.
Abstract: Soil Sci. Soc. Am. J. doi:10.2136/sssaj2013.07.0302 Received 26 July 2013 *Corresponding author (lotfollah.abdollahi@agrsci.dk; Lotfollah.abdollahi@yahoo.com) © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Tillage System and Cover Crop Effects on Soil Quality: II. Pore Characteristics Soil & Water Management & Conservation
TL;DR: In this article, the importance of leaves and roots on soil C and soil organic matter (SOM) quantity and quality were measured in a temperate deciduous forest for 20 years.
Abstract: Above- and belowground litter inputs in a temperate deciduous forest were altered for 20 yr to determine the importance of leaves and roots on soil C and soil organic matter (SOM) quantity and quality. Carbon and SOM quantity and quality were measured in the O horizon and mineral soil to 50 cm in five treatments (control, double litter [DL], no litter [NL], no roots [NR], no inputs [NI]). After two decades of doubled litter addition, soil C and SOM did not increase. However, leaf litter exclusions reduced soil C (O and mineral horizons combined) by 24% in NL and 33% in NI treatments. In the mineral soil, the largest declines occurred in the 0- to 10-cm depth (0.93–2.01 kg C m⁻²), although losses were observed throughout the entire solum. The NR treatments showed no losses of C. Thermal characterization of SOM quality differed among treatments in the 0- to 10-cm depth. Patterns of CO₂ evolution during SOM combustion revealed differences in SOM quality between surface and deeper horizons. Our work shows that the sources of litter are important in controlling soil C. Leaf litter made important contributions to maintaining current stocks of soil C; increased leaf litter did not increase soil C, but decreases in litter inputs resulted in rapid soil C declines. Root litter may ultimately provide more stable sources of soil C. Management activities or environmental alterations that decrease litter inputs in mature forests can lower soil C content; however, increases in forest productivity and the resulting increased litter production seem unlikely to increase soil C sequestration.
TL;DR: Liang et al. as discussed by the authors presented a paper on the 11th Dahlia Greidinger Memorial Symposium: Advanced Methods for Investigating Nutrient Dynamics in Soils and Ecosystems.
Abstract: Soil Sci. Soc. Am. J. 78:47–53 doi:10.2136/sssaj2013.05.0159 Received 2 May 2013. *Corresponding author (liang410@zju.edu.cn). Supplemental materials are available online. © Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and AgriFood Canada All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Molecular Speciation of Phosphorus Present in Readily Dispersible Colloids from Agricultural Soils The 11th Dahlia Greidinger Memorial Symposium: Advanced Methods for Investigating Nutrient Dynamics in Soils and Ecosystems
TL;DR: In this paper, the authors investigated the effects of near soil surface characteristics on soil detachment by overland flow in a 7-yr restored natural grassland in the Loess Plateau of China.
Abstract: Vegetation restoration probably has great effects on the process of soil detachment This study was conducted to investigate the effects of near soil surface characteristics on soil detachment by overland flow in a 7-yr restored natural grassland Four treatments were designed to characterize the effects of dead roots, live roots, biological soil crusts (BSCs), and plant litter-stems in succession For comparison, an undisturbed bare Loess soil was used as a baseline The testing area (10 m in length and 01 m in width) of each treatment was subjected to flow scouring under five different shear stresses ranging from 6 to 13 Pa The results showed that near soil surface properties of plant litter-stem, BSCs, and plant roots enhanced the resistance of soil to water detachment significantly With these factors subsequently superimposed, soil detachment capacity decreased progressively Taken together, the 7-yr restored natural grassland would decrease soil detachment capacity by 989% compared with the bare Loess soil, in which plant litter-stem, BSCs, and total roots contributed to 303, 149, and 537%, respectively Furthermore, for the total root effects, chemical bonding of root exudates accounted for 147% while physical binding of root systems accounted for 390% Results also indicated that BSCs were unable to protect the soil from detachment when the shear stress was greater than 11 Pa, and tended to accelerate soil erosion This paper developed an equation for adjusting WEPP’s rill erodibility for use in natural succession grassland in the Loess Plateau of China, and the result seemed satisfactory with the Nash-Sutcliffe efficiency (NSE) coefficients ranging from 028 to 077 Further studies are needed to detect the dynamics of near soil surface characteristics with succession age of grassland in the Loess Plateau
TL;DR: In this article, the characteristics of intra-aggregate pores and their relationships with bacterial community composition in 4-to 6-mm soil macroaggregates from two contrasting agricultural systems, namely a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.]-wheat (Triticum aestivum L.) rotation (i) with conventional chemical inputs and (ii) without chemical inputs but with legume cover crops.
Abstract: It is known that variability in the characteristics of soil physical microenvironments, e.g., locations and characteristics of soil pores, can have a major influence on microorganisms. This study compared the characteristics of intra-aggregate pores and their relationships with bacterial community composition in 4- to 6-mm soil macroaggregates from two contrasting agricultural systems, namely a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.]–wheat (Triticum aestivum L.) rotation (i) with conventional chemical inputs and (ii) without chemical inputs but with legume cover crops. Characteristics of intra-aggregate pores and particulate organic matter (POM) were obtained from three-dimensional X-ray computed microtomography aggregate images at 13-μm resolution. Microbial community analyses were conducted using 16S rRNA pyrosequencing. We found that the aggregates from long-term (>20 yr) organic management with cover crops differed from the aggregates from conventional management in terms of intra-aggregate pore-size distribution, intra-aggregate pore variability, POM contents, as well as microbial community compositions. Relative abundances of Actinobacteria, Proteobacteria, and Firmicutes in the aggregates from cover-crop-based management were positively correlated with the presence of large (>110 μm) pores, while the presence of medium-sized pores (32–84 μm) was significantly correlated with 30 to 40% of the top 100 bacterial operational taxonomic units identified during sequencing. The results suggested that the legacy of rhizosphere presence in terms of intra-aggregate pore structure and microbial community composition can last in the studied soil for at least 4 to 9 mo. Our study demonstrated that working with bulk sieved soil samples can mask substantial differences present within distinct soil aggregate units.
TL;DR: In this paper, the impacts of different degrees of soil drying (drying to 45, 30, 20, or 10% water-filled pore space, WFPS) and subsequent rewetting (rewetting to 75 or 90% WFOPS) on N₂O emissions, denitrification, and net N mineralization were investigated.
Abstract: Soil drying and subsequent rewetting induces N mineralization and denitrification, but the effects of the “extent” or “degree” of drying and rewetting remains poorly understood. The impacts of different degrees of soil drying (drying to 45, 30, 20, or 10% water-filled pore space, WFPS) and subsequent rewetting (rewetting to 75 or 90% WFPS) on N₂O emissions, denitrification, and net N mineralization were investigated. The highest N₂O emissions (201 µg N₂O-N kg⁻¹) occurred when the soils were dried to 10% WFPS followed by rewetting to 90% WFPS, whereas the lowest emissions (4.72 µg N₂O-N kg⁻¹) occurred when the soil was dried to 45% WFPS followed by rewetting to 75% WFPS. When soil was rewetted from 10 to 90% WFPS, cumulative N₂O emissions over 120 h were 7.4 times greater than when the soil was rewetted from 10 to 75% WFPS. The proportion of N₂O evolved [N₂O/(N₂O+N₂)] generally increased as the soil dried. Soil rewetting to 75% WFPS generally produced greater N₂O/(N₂O+N₂) ratios than rewetting to 90% WFPS. Net N mineralization rates in soils rewetted to 75% WFPS significantly increased from 0.78 mg N kg⁻¹ d⁻¹ for the soils dried to 45% WFPS to 1.69 mg N kg⁻¹ d⁻¹ for the soils dried to 10% WFPS. More extensive soil drying and more extensive rewetting stimulated N₂O emissions and total denitrification losses, whereas net N mineralization rates were stimulated only by more extensive drying. Management practices which reduce extreme fluctuations in soil water content may consequently reduce N₂O and total denitrification losses.
TL;DR: In this article, a laboratory rainfall experiment with deionized water was conducted to examine the process of rill evolution and the relationship between runoff, rill development, and erosion rates for clay loam and loess soils given a fixed slope gradient (10 degrees) and two rainfall intensities (1.5 and 2.0 mm min(-1)).
Abstract: Rill erosion accounts for approximately 70% of the total erosion of upland areas in China's Loess Plateau. A laboratory rainfall experiment with deionized water was conducted to examine the process of rill evolution and the relationship between runoff, rill evolution, and erosion rates for clay loam and loess soils given a fixed slope gradient (10 degrees) and two rainfall intensities (1.5 and 2.0 mm min(-1)). The results show that rills evolved from a series of parallel drop-pit chains along the down-slope direction. Clay loam soil produced rills under a rainfall intensity of 1.5 mm min(-1), and loess soil produced rills only under higher rainfall intensity. The temporal change in sediment concentration and erosion rate shows good consistency with the emergence of drop pits and rills. An increase in rainfall intensity had little effect on the sediment concentration and erosion rate for clay loam soil, whereas for loess soil, both increased rapidly and exceeded those of clay loam soil, with the emergence of a rill when the rainfall intensity was higher. Rills have a much greater effect on sediment concentration and erosion rate for loess soil than for clay loam soil. This study indicates that soil texture has a major impact on rill formation; clay loam soil is more subject to rill formation, but the rills formed are generally small and do not substantially increase soil loss. In contrast, the well-developed rills in silt loam soil can result in intensive soil loss, though rills occur infrequently. Basic understanding of these results, causes, and quantification are essential for the prediction and evaluation of soil loss.
TL;DR: Jabro et al. as discussed by the authors studied the effects of repeated freeze-thaw cycle cycles on soil compaction in a Clay Loam in Northeastern Montana, and found that the cycle was associated with a significant increase in soil saliency.
Abstract: Mention of trade names, proprietary products, or specific equipment is intended for reader information only and constitutes neither a guarantee nor warranty by the ARS-USDA, nor does it imply approval of the product named to the exclusion of other products. Soil Sci. Soc. Am. J. 78:737–744 doi:10.2136/sssaj2013.07.0280 Received 12 July 2013. *Corresponding author (jay.jabro@ars.usda.gov). © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Repeated Freeze-Thaw Cycle Effects on Soil Compaction in a Clay Loam in Northeastern Montana Soil Physics
TL;DR: In this article, seasonal changes in soil organic C were studied in a field experiment with winter wheat (Triticum aestivum L.) in the Pacific Northwest, United States.
Abstract: Long-term changes in total soil organic C usually occur gradually. These long-term trends might be obscured by smaller, rapid changes in soil C due to seasonal inputs of plant residues, roots, and exudates, or decomposition of such inputs. Yet there is little, if any, data describing the magnitude of seasonal changes in soil C. If seasonal fluctuations in soil C are substantial, then important implications exist for accurate comparison of soil C between sites, between treatments, and even in the same experimental unit over time. Thirty-nine consecutive monthly soil samples were taken from a field experiment planted every year with winter wheat (Triticum aestivum L.) in the Pacific Northwest, United States. The variation in soil organic C was 14 to 16% of the mean over the 39-mo period in the top 250 kg m⁻² equivalent mass (∼0- to 20-cm depth). Two to eight percent could be identified as a regular seasonal pattern. The no-till management system had the greatest seasonal fluctuation, and the timing of the annual maximum was different from that of the tilled soil management treatments. In the shallower soil layer (∼0–7 cm), total soil organic C varied 12 to 29% in which 4 to 13% could be attributed to a 12-mo seasonal pattern. Given the small magnitude of changes in soil C being measured and modeled in many agricultural and natural systems, soil samples taken at a single point in time are likely to encounter substantial but hidden measurement variability. The variability may be compounded by factors of the timing of sampling in relation to natural soil organic matter cycles and differences in the cycle due to treatment and weather. Sampling plans, which account for seasonal fluctuation and the different fluctuation patterns under different soil situations, will improve measurement accuracy.
TL;DR: In this paper, the short-term (3 yr) cumulative impacts of stover removal with and without winter rye (Secale cereale L.) cover crop or animal manure application on near-surface (0-to 5-cm depth) soil properties under irrigated no-till continuous corn on a Hastings silt loam (fine, smectitic, mesic Udic Argiustolls) near Clay Center, NE.
Abstract: Addition of cover crops and animal manure following corn (Zea mays L.) stover removal for expanded uses may mitigate negative soil property effects of stover removal. We studied the short-term (3 yr) cumulative impacts of stover removal with and without winter rye (Secale cereale L.) cover crop or animal manure application on near-surface (0- to 5-cm depth) soil properties under irrigated no-till continuous corn on a Hastings silt loam (fine, smectitic, mesic Udic Argiustolls) (<3% slope) near Clay Center, NE. Treatments were irrigation levels (full and deficit), amelioration practices (none, cover crop, or animal manure), stover removal (no removal or maximum removal), and N fertilization (125 or 200 kg N ha⁻¹). Data collected after 3 yr indicate that stover removal (63%) reduced geometric mean diameter of dry aggregates 93%, increased erodible fraction sixfold, and reduced aggregate stability 32% compared with plots without stover removal. Stover removal from plots with cover crop or manure reduced dry aggregate size and stability and increased erodible fraction compared with plots without removal and amelioration practices, indicating that amelioration practices did not offset stover removal effects. Stover removal reduced wet aggregate stability and soil organic C (SOC) concentration in the 0- to 2.5-cm depth, but cover crop or manure mitigated these small reductions. Stover removal did not change water infiltration rates and had small effects on particulate organic matter (POM). Overall, in the short term, cover crop or manure may not provide sufficient protection from raindrop impact and wetting and drying cycles to maintain soil structure, resulting in increased susceptibility to wind erosion. Use of these amelioration practices, however, may offset changes in surface layer wet aggregate stability and SOC after high rates of stover removal in this region.
TL;DR: Wall et al. as discussed by the authors evaluated soil tests for predicting Nitrogen Mineralization in Temperate Grassland Soils Nutrient Management and Soil & Plant Analysis, and concluded that soil tests can be used to predict nitrogen mineralization.
Abstract: Soil Sci. Soc. Am. J. 78:1051–1064 doi:10.2136/sssaj2013.09.0411 Received 24 Sept. 2013. *Corresponding author (david.wall@teagasc.ie) © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Evaluation of Soil Tests for Predicting Nitrogen Mineralization in Temperate Grassland Soils Nutrient Management & Soil & Plant Analysis